The heterogeneous network (HetNet) is envisioned as a promising component of cellular network to meet the ever-increasing demand for mobile broad services. In HetNet, both spectral efficiency per unit area and transmit efficiency can be improved significantly by shrinking cell size via the deployment of Low-Power Nodes (LPNs) in the coverage of macro Base Station (BS), which is referred to as macro cell below. Thus in HetNet, the coverage of LPN, which is referred to as LPN cell below, is within one macro cell. Combining full frequency reuse, we can conclude the interference between macro BS and LPN is a serious concern in HetNet.
In the prior art, the network-centric enhanced inter-cell interference coordination (eICIC) technique has been intensively studied in the 3rd Generation Partnership Project (3GPP) community. In eICIC, the macro cell is prevented from transmitting data in certain subframe, which are referred to as Almost Blank Subframe (ABS). During ABSs, LPN cells can schedule User Equipments (UEs) that would otherwise experience too high interference from the macro cells.
However, it is founded by the inventor that although the interference experienced by the UE serviced by the LPN cell can be reduced on the specific time/frequency resource of the macro cell by the prior art, there are still the following problems.
Because the macro cell will still transmit Cell-specific Reference Signals (CRS) located in ABS, the interference from the macro cell experienced by the UE that is served by the LPN cell can only be eliminated partially. The remaining interference from the above CRS declines the performance of UEs served by LPNs. The above problem becomes more serious when the Range Expansion (RE) technique is employed to achieve the load balancing between the macro cell and LPN cell. In RE technique, the power received by UEs from LPN cell is artificially increased by adding a fix bias. Thus, some UEs are actively pushed into LPN cells. Under this situation, the remaining interference from the CRS of the macro cell causes the more seriously negative impact on the UEs served by LPN. Furthermore, in a practical system, the traffic is time-variant, and since the configuration of the ABS subframe is half-static, whenever the UEs served by the macro cell require the data transmission, it must wait for the non-ABS subframe to receive the service. The above process will cause the delay on the data transmission and affect the performance of these UEs.